This invention relates to granular phenolic-urethane molding compounds suitable for the preparation of molded articles having improved mechanical and electrical properties. More particularly it relates to granular molding compositions derived from hydroxyl terminated polydienes, hydroxyalkylated novolacs and polyisocyanates.
A wide variety of polyurethane compositions are known and used commercially in the preparation of molded articles, laminates, coatings, films, adhesives, rigid and flexible foams and the like. The great variation of polyurethane compositions and properties thereof stems from the ability of isocyanates to react with a wide variety of organic compounds having active hydrogen-containing groups. Among the many such compositions known in the art are polyurethanes prepared from polyisocyanates and various polyols, including for example polyether polyols, polyester polyols, polydienediols, novolacs, hydroxyalkylated novolacs and others. Thus, for example, in U.S. Pat. No. 3,728,293 it is disclosed that polyurethane compositions derived from specific mixtures of polyether polyols, novolac resins, and polyisocyanates, possess improved physical properties and self-extinguishing characteristics.
It is also known from U.S. Pat. No. 3,515,699, that thermoset molded articles, such as battery containers may be prepared from liquid reaction mixtures comprising an hydroxy-terminated polydiene, a polyether polyol and an organic diisocyanate.
It is further known from U.S. Pat. No. 3,515,772 that thermoset polymeric resins may be prepared from polydienes having functional end groups such as hydrogen or carboxy, a polyfunctional polyether, and a chain extender such as an organic diisocyanate or a polyanhydride such as an epoxy novolac.
Furthermore, it is known from U.S. Pat. No. 3,497,465 to prepare polyurethanes especially useful in low temperature applications from the reaction of an organic polyisocyanate with a composition comprising an hydroxyalkylated phenol-aldehyde resin, a polyol prepared by reacting a polyhydric alcohol and a mono epoxide, a dihydric alcohol such as ethylene glycol, an alkanolamine, and a phosphorus compound.
These and other polyurethane compositions provide a wide selection of desirable properties. Despite this wide selection of known compositions and properties, industry is constantly seeking new and better components and specific combinations of components for polyurethane compositions that will provide improved properties for various special applications.
Accordingly, it is an object of the present invention to provide granular molding compounds suitable for the preparation of molded polyurethane articles having excellent mechanical and electrical properties. It is a further object to provide novel and useful polyurethane compositions and articles prepared therefrom. These and other objects and advantages of the compositions of this invention will be apparent to those skilled in the art from the detailed description that follows.